I loved the ending, shots and song and everything (cheese and all). Of course I could have done without the second shots of non NHB (like Millie, Chase, ect), but it didn't bother me.
A sadder toned song would have ruined the mood, IMHO. The end had no tint of sadness at all (they are all happy and content and at a celebratory game) and the shots of NHB looking at their younger selves was enough for me to get the nostalgic sad feeling that we won't see their journey's on screen anymore. That was enough & had me teary. Us against the world was great for ep 11. The song One Tree Hill playing for the end of the show OTH, is fitting and the beat wasn't that upbeat like a dance song...it was slow enough to feel nostaglic but happy enough to make us feel that their lives are good.